Synthesis of corannulene

MP2 and DFT Calculations on Circulenes and an Attempt to Prepare the Second Lowest Benzolog, [4]Circulene

“…The simplest circulene is hence [3]circulene (1), the next higher benzolog is [4]circulene (2) and so on (Scheme 1).…”

“Deconvoluted Fullerene” Derivatives: Synthesis and Characterization

“…In fact, it is well-known that the alkoxy groups directly linked to the fullerene carbon cage play a major part in lowering the LUMO due to the prevalent electronegative inductive effect. [19] Furthermore, it should be mentioned that the location of the HOMO/LUMO energy levels is similar to those of any functionalized C 60 , such as 1-(3-methoxycarbonyl) propyl-1-phenyl- [6,6]-C 61 (PCBM) [20] and therefore, accessible to a large number of donating polymers for their use as acceptors in bulk heterojunction (BHJ) solar cells. [21] Optical and electrochemical energy gaps differ only by as much as 0.16 eV and 8 c presents the lowest value among these derivatives of approximately 1.55 eV, due to the more extended p-conjugated system.…”

Ring-Current Assessment of the Annulene-Within-an-Annulene Model for some Large Coupled Super-Ring Conjugated-Systems

“…No knowledge or assumptions of any other parameters are required for an application of the HLPM 1-8 method. 11,12 The present authors have applied this technique to a wide variety of extant and hypothetical conjugatedsystems, 1,[13][14][15][16][17] primarily in order to test the so-called 'Annulene-Within-an-Annulene (AWA) Rule' 1,[13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] for what have been described as 'super-ring' structures. 1,[30][31][32][33] A general super-ring conjugated hydrocarbon is illustrated in Figure 1 (which is taken from Ref.…”

“…18 As is seen from Figure 8, the hydrocarbon is a super-ring system with a [5]-membered central ring and a [15]-membered perimeter. Barth and Lawton rationalised 18,19 the apparent stability of this species by explicitly devising the AWA model for the express purpose of discussing corannulene and postulating that, by transfer of one electron from the outer region to the central ring, 18,57 corannulene could be modelled 20 as a 6-π-electron cyclopentadienyl anion within a 14-π-electron annulenyl cation. As Steiner et al 20 have pointed out, this assumption would require what they call 'con-rotatory rim and hub currents' 20 that is, currents circulating in the same sense (and, here, it has to be the anti-clockwise sense -diamagnetic) around both the inner ring (which, by analogy with a wheel, they call the 'hub' 20 ) and the outer perimeter (what they call the 'rim' 20 ).…”

“…In practice, ipso-centric abinitio ring-current calculations, 20,36 as well as those 14,57 based on the topological HLPM formalism, 1-8 contradict this requirement: there is agreement 14,20,57 between these two approaches (ab-initio 'ipso-centric' 20 and HLPM 'topological' [1][2][3][4][5][6][7][8]20,57,58 ) of considerably different sophistication that there is a parametric circulation in the central ring and a diamagnetic one around the perimeter. Other theoretical studies 59,60 have likewise since cast doubt on the validity of Barth and Lawton's original hypothesis, 18,19 invoked in order to account for the stability of corannulene (10).…”